Enzymes in Diagnosis Flashcards
How are enzymes used as diagnostic markers?
Enzyme activities measured in a serum
What may imply tissue damage?
- Reduced levels of enzymes
- Intracellular enzymes in serum
- Distribution of enzymes in different tissues
Why is leakage of intracellular enzymes into the blood dangerous?
Time after injury is crucial since enzymes have a different half-life in the blood stream
What is enzyme activity measured in?
Expressed in standard units so that values between clinical labs can be compared
- Standard measure = International Unit (UI)
What is 1 UI?
The amount of activity that will convert 1 micromole of substrate per minute under standard defined conditions
What does a spike in enzyme activity precede?
Any liver damage
What is increase of bilirubin normally an indicator of?
Jaundice
What do elevated GOT levels indicate?
Normal 6-48/L
Acute liver damage
What can albumin levels indicate?
Normal: 3.5-5.3/dL
Indicates loss of liver secretory function
What can GPT levels indicate?
Normal: 7 to 55 IU/L
More specific indicator of liver damage
What can alkaline phosphatase (ALP) levels indicate?
Normal: 45-120 IU/L
Elevation indicates large bile duct obstruction
What is prothrombin time (INR)?
Measure of a patient’s ability to clot blood
What are the cardiac injury markers?
- Creatine kinase
- Myoglobin
- Cardiac Troponin-I
- Lactate dehydrogenase
What does creatine kinase release indicate?
Release indicated muscle damage
Creatine phosphate acts as a store of high energy phosphate groups in muscle
Reverses reaction when needed to get a burst of ATP
What 2 polypeptides does creatine kinase (CK) comprise?
M and B subunits
What structure of CK is mainly found in skeletal muscle?
MM (increase with AMI but also with skeletal muscle injury)
What structure of CK is mainly found in the myocardium?
MB
What is paracetamol overdose treated with?
Treatment with N-acetylcyseine with methionine
What are typical blood glucose levels?
0.8-1.0
What is level is hypoglycaemia?
<0.5 mg/ml
What level is hyperglycaemia?
> 1.8 mg/ml
What enzyme is important in childhood leukaemia? Why?
- Tumour cells deficient in Asn synthetase, therefore Asn becomes essential
Treatment - Deliver asparaginase
- Breaks down asparagine into aspartate
- Makes plasma levels of asparagine lower, specifically affecting growth of tumour cells
What enzyme is given during coronary thrombosis and why?
- Serine protease actin on fibrin clots
- Produced using recombinant DNA technology
- Rapid application can significantly increase chances of surviving coronary thrombosis
What is urease used to break down?
Urease is used to breakdown the urea that builds up in patients with compromised kidney function
